Inclinometer and compass indicating means for grounded aviation trainers



Oct. 18, 1949. s, 1, HAYES INCLINOMETER AND COMPASS INDICATING MEANS FOR GBOUNDED AVIATION TRAINERS Filed Jan. 2, 1948 09 N9 02 92 mm. mm. 7 mo. 3 I m2 8 E mm. .8 wmm .EN 1 .NQN m R Kama om 0m. m w on I 5 91%. 2 ws rw bl- I s wm w gm N En ww 2. 33$ 3 $1 M" 9% 3 7 8N mom. fimw pwmmmo I mmm m8 m9 2m 3m mom MMK 9m x 9. 0mm mm A o N9 3N v w: m2 8w 0 we. N Q? o A 09 3 N9 g. m2 5 mm. 2w. 3. N2 N2 8. 8. 2 Na Patented Oct. 18, 1949 INCLINOMETER AND {COMPASS INDICAT- ING MEANSFOR GROUNDED AVIATION TRAINERS A l Stanley I.,:Hayes, Binghamtcn, N. assignor to Link Aviation, 1110., Bin poration of New York ghamton, N. Y., a cor- Applicationanuary 2, 1948, S erial No. 327

This invention relates to inclinometer and 'com'-, pass indicating means for use in grounded aviation trainers, and will be disclosed in conjunction with aviation trainers of the type covered by United States Patents 1,825,462 and 2,099,857 issued to Edwin A. Link, Jr.

Real aircraft generally carry an instrument known as the inclinometer which comprises a tube mounted upon the instrument panel and a ball placed inside the tube to move along the axis of the tube relative to neutral graduations thereon to indicate to the pilot of the plane the correct coordination of the banking and turning controls in the plane whenthe plane is being turned and banked. In the case of a-properly coordinated turn, the ball in the tube remains centered with respect to the graduations thereon, while in the case of an application of insufficient bank simultaneously with the turn, the ball moves in the opposite direction of the turnto' indicate that a skidding turn; is being made." on the other hand, in case the planeis banked'too greatly for the rate of turn the ball'moves away from the neutral graduations on the tube iri the direction of the turn toindicate to the 'pil'otthat aslippingturnisbeingmade. I h j In the case of real aircraft, a'correct turn is accomplished by proper coordination of the stick and rudder pedals in the plane, andin order ;to

simulate the functioning of the inclinometer in, I

amount of stick and rudder pedals are-applied the ball in the inclinometer tube remains centered, thus indicating tothe student that a correct simulated turn is being-madew When insllfilciel'lt rudder is applied for the degreeof bank of the turn, the previously described interconnecting means operate the inclinometer tube to move the ball away from the center of the tube opposite the direction of turn to indicate-that a simulated skidding turn is being madeand when too much stick is applied for the rate of turn the inclinometer tube is moved by-the previously described differential interconnecting means to move the ball away from. the central graduations upon the tube toward the direction of bank to indicate that a. slipping made. V

When the invention :is .employeddniconjunce tionrwitha fuselage arrangedltoltilt to simulate. 55;"- platellaalwhich isrheld byjpiyotrldfl whichintum;

turn is being a Qlaiins. (01. 35-12) plate I30 and upright I32.

the banking of a plane, an additional connection responsive to the banking position of the fuselage may also beemployed to offset at least in part thefmo'vement of the ball as a result of the physical banking of the fuselage.

--.In order that the detailed nature of this in-' vention may be clearly understood, reference is made to the accompanying drawings, wherein, Fig, 1 is a perspective-viewishowing the'essen-' tialparts of-this inventiomand .0 V Fig. 2 is a perspective view showingthe detailed mounting of the -inclinometer tube. Reference is made toFig. 1 where the conven tional simulatedstick control is designated I00, the --lower end of this'control stick passing through the slot I02 in shaft- I04 which is r0 tatably mounted inthe two brackets I06 which are suitably affixed upon the floor I 08 of the fuselage of the trainer by means of the bolts I I0 which pass-through the base plate I I2 whichis formed integrally with brackets I06. The stick I 00 is pivoted upon the pin H4 which passes through the shaft I04 'and the slot I02 so that the stick may-be moved in either direction transversely of the trainer fuselage'to simulate-the motipnimparted to the stick inareal plane when the pilot desires to bank the plane to theleft or right. By virtue of the'fa'ct that shaft I04 is rotatably mounted in the brackets" I06, thestick' momay bemoved fore and aft to simul ate the motion imparted to the stick; inareal plane when the pilotdesires to change the pitch attitude of the P ane Carried by the lower endof stick I00, i the bjalliflfi which engages the fingers ,I I8 integral withjthecap I20 of, the mainflcont l,valvegdes ignated generally by I22. For a detailed dis-- closure of the construction and operation of the. main control valve I22, reference may be had to the copending application. of Stanley I. Hayes and Theodore Herskovits,. Serial Number. 328

filed January- 2, 1948 for Main and auxiliary control valve arrangement'for grounded aviation trainer. h a u Connected to the ball II 6 is the rod I24 to the outer; end of which is attachedthe left end of link hI26 which runs transversely. of the trainer fuselage and passes through the hole I28 in the- Plate I30 is aflixed to, the upright I32,by means of bolts I34, and upright I32 runs longitudinally of the fuselage and is suitably, aflixed to, the base I08. The right end of link I26, is, attached by, pivot I36 to the 3 is carried by bracket I42 which is attached to plate I30 by the bolts I44.

The forward end of the link I46 is pivoted to plate I38 by pivot I48, and it will be appreciated that the plate I38 is in effect a bellcrank. The rear end of link I46 is pivoted upon the pin I50 which is affixed to the upper end of the arm I52 and which also passes through the upper end of arm I54 which is freely mounted upon this pin. The lower end of arm I54 is pivoted upon the stud I56, the inner end of which is carried by the plate I30. The lower end of arm I52 is aflixed to the stud I58 upon which the lower end of the arm I60 is freely mounted, the stud I58 having an enlarged diameter I62 for spacing the two arms I52 and I60. The three arms I52, I54 and I60 and associated parts form a differential device, the operation of which will presently appear.

The adjustable screw eye I64 passes through the center of arm I60 and is affixed thereon by means of nut I66, and the rear end of cable I 68 is attached to the forward end of screw eye I64. Cable I68 passes around the pulley I10 which is freely mounted upon the stud I12 carried by bracket I14 which in turn is carried by the member I16 aflixed to th longitudinally extending member I32, and then cable I68 turns to run upwardly around pulley I18. Pulley I18 is freely mounted upon the stud I80 carried by the instrument panel I82, and at pulley I18 cable I68 turns to run transversely of the fuselage and around pulley I84 which is freely mounted upon the stud I86 also carried by the instrument panel I82. Cable I68 then is turned to run back toward the right side of the fuselage, the end of cable I68 being attached to the upper end of arm I88.

Referring now to Figs. 1 and 2, it will be seen that the arm I88 is affixed upon the forward end of shaft I90 which is suitably rotatably held by the plate I82 which is attached to the instrument panel I82 by means of studs I84. Upon the rear end of shaft I90 is affixed the plate I86 to which the inclinometer tube I98 is affixed by mean of the wires 200. A butterfly openin I89 is cut in the instrument panel I82 through which the inclinometer tube I88 is visible. The tub I88 contains a suitable damping fluid and the ball 202 which is slightly smaller than the interior diameter of the tube I88 so that it will roll within the tube in response to a movement of the tube I88 about the axis of shaft I80. The wires 200 also constitute a pair of index lines which are spaced by a distance equal to the diameter of the ball 202, each Wire being offset from the center of tube I88 by an amount equal to one-half the diameter of ball 202. The left end of tension spring I95 is aflixed to the upper end of arm I88, the right end of this spring being anchored to stud I81 carried by panel I82.

The arm I88 carries the pin 206 which lies between the bifurcations of the lower end of arm 208, the upper end of which is affixed upon the rotor 2 I rotatably mounted in the case 2I2 carrying the compass scale 2. Affixed upon the rotor 2I0 are the conventional metallic North- South compass adjusting elements 2 I 6. The compass case 2I2 is suitably aflixed to the instrument panel I82 by means of brackets and screws 2 I 8 and 220.

Referring back to Fig. 1, it will be seen that the left and right rudder pedals are designated by 222 and 224 and are aflixed upon the rudder bar 226 by means of pins 228. The rudder bar 226 is afiixed upon the vertical post 230 upon main valve I22.

which is affixed the arm 232, the lower end of the rudder post 230 being rotatably held in the bearing block 234 held by the fixed member 236 which is suitably located inside the trainer fuselage. To the outer end of arm 232 is pivotally attached the forward end of link 238, the rear end of which is pivotally attached to the arm 240 integral with the rudder leaf 242 of the The forward end of the cable 244 is attached to the arm 240, and this cable extends rearwardly of the fuselage to encircle the pulley 246 which is freely mounted upon the vertical stud 248 affixed to the bottom I08 of the fuselage. Cable 244 then runs transversely of the fuselage and then passes through the hole 250 in the plate I30 and vertical member I32, and then around the pulley 252 which is freely mounted upon the stud 254 carried by bracket 256 which is affixed to plate I30 by screws 258. The rear end of cable 244 is attached to the adjustable screw eye 260 which passes through the center of the arm I52 and which is held on arm I52 by the nut 262. The adjustable screw eye 260 also carries the clip 264 to which the forward end of the tension spring 266 is attached, the rear end of this spring being carried by the transversely extending portion of the plat I30.

The upper end of the arm I60 carries the adjustable screw eye 268, by means of nut 210, and the rear end of this screw eye carries the clip 212 to which is attached the forward end of the compression spring 214, the rear end of this spring being held by the transversely extending end of plate I30. The rear end of cable 216 is attached to th forward end of screw eye 268, and this cable passes around the pulley 218 which is freely mounted upon stud 280 carried by bracket 282 which is afllxed to plate I30 by means of screws 284. Cable 216 passes through the hole 286 in plate I30 and member I32, and the other end of this cable is attached to the lower end of arm 280 which is aflixed upon the longitudinally extending rod 292 by means of set screw 294.

Considering now the detailed construction of the universal joint which supports the trainer fuselage relative to the stationary base, as is well known to those skilled in the art, it will be seen that the base plate 296 is aifixed upon the floor I08 of the fuselage by means of bolts 298, and integral with the base plate 286 is the outer gimbal 300. .The inner gimbal is designated 302 and is freely mounted upon the pin 304 which is fixedly held by the upper end of the vertical spindle 305 which is rotably mounted in the stationary base of the trainer, as is also well known to those skilled in the art. The inner gimbal 302 is freely mounted upon the stud 304 to move about the transverse axis 306. The outer gimbal 300 is freely mounted upon the rod 282, the rear end of which is affixed in gimbal 302 by means of set screw 308, and the rod 282a has its rear end pivotably mounted in the outer gimbal 300 while its forward end is pinned to the inner gimbal 302 by means of pin 3I0. The rods 282a and 282 are co-axial, and their axes form the longitudinal axis 2821).

By virtue of this construction it will be appreciated that when the fuselage is banked to the left by a movement to the left of stick I00, as is well understood by those skilled in the art, the gimbal 302 does not move, but that the outer gimbal 300, floor I08 and all parts afiixed thereto will rotate counterclockwise about the longitudi- 7 nal axis 282b, as seen from the rear, and that when the fuselage is ibankedzto' the right vby an opposite movement of .s'tick'tl00 :thesamewparts will move inthe opposite:directionraboutnaxis 2921). When the nose of the fuselage'iisrlowered by a forward movement of stick .L00', bothj.ginf'- bals 302 and 300 rotateclockwiseiabouttthe transverse axis 306, as seen from the right side' of 'the fuselage, and the floor I08 and all parts aflixed thereto move in the same direction. When the fuselage pitching action is reversed 'to raisethe nose of the fuselage in response to a rearward movement of stick I00, the samecpartsimove about the transverse axis 306:.in th'e opposite direction.

Inasmuch as upon a banking of the fuselage the inner gimbal 302 does not move, it will be appreciated that the shaft 292 similarly "does not move, and that the arm 290 afiixed upon the forward end of this shaft'remains vertically disposed at all times.

Operation fv Assuming that the student in the trainerimoves the control stick I00 to the left to bank thfuselage to the left, but retainsthe, rudder pedals 222 and 224 in their centered positions,.the,link I26 will move to the right rotating the bellcrank I38 counterclockwise as seen ,from above, and moving the link I46 aheadThe arm I54 will be rotated clockwise as seenfrom the rightQabout the pivot I56 and the upper end of arm,l52'will move with the upper end of arm I54. The spring 266 and cable 244 hold the screw eye 260 from moving fore and aft, thus providing a-pivot for arm I52, and the lower end. of. arm I52 moves to the rear. The stud I58 andlowerend ofaarm I60 move in the same directiomspring' 'zu ana cable 216 providing a pivot for the upper end of arm I60. The rearward movement of, the lower end of arm I 60 will result in a similar movement of the lower end of cable I68, and .thisicable will be pulled to move the upper end of arm 'I 88 tofthe left, rotating this arm, and the tube I98 of the indicator counterclockwise as seen by. the student. This rotation of the tube I'9'8 willres ult' inga movement of the ball '202to th'lef t, 'thus'ir'i dicating to the student that theftra'i'ner in a simulated slipping left turn.' Afssuinifigllthat to correct this faulty simulated handlingjof the fuselage, the student then moves the left 'riidder pedal 222 ahead, link 238 will move inthe same direction and cable 244 will be pulled to move the screw eye 260 ahead, resulting i a counterclockwise rotation. of the arm ,I52 about the pivot I50. The stud l58 will move ahead as will the lower end of the arm I60, arm I60 pivoting about the screw eye 268 he ld tby spring; 214 and cable 216, and the cable I68 will-be 'released by an amount dependent upon-the forward movement of the rudder pedals 222, The spring I85 will rotate the arm I88 and inclinom eter tube I98 clockwise as seenby the student, and the ball 202 will move backv toward gthe center of the tube I98. Ifthe student; applies just the correct amount of left rudder, the ball 202 will be returned to its centered positionwith respect to the index wires 200 upon the'tube I98, and then the rate of turning of the fuselage will be correct for the degree of bank.' ,'An insufficient amount of application of11efl :Iudder will only partially return the ball to its neutral position, thus indicating to the student that even more left rudder must be applied, anduaneovere application of left rudder will result in a rotation of the tube I98 clockwisees thaktheball 202arnoves-tothe right of the wires 200' upon the tube, thus indicating tothe student that an overapplication of left rudder has been applied and that the :trainer is in a simulated skidding left turn; 5:1

*sthesfuselage starts to bank to the left, the instrumenttpaneltand tu'be I98 are tilted to the left; andrtliecball 202 moves to the left of its neutral'rposition. By virtue of the fact that am 290Tiremainsr-yertical, and the distance from the lower endiof .arm' 290 to the stud 280 uponwhich pulley 216is mounted increases with a left bank, cable-2 16 is pulledresulting in a forward movementofithe-upper'end of arm I60, and in a releasing of ica'ble'li I68, resulting in a clockwise rbtationiofrtube :I98; However, the clockwise rotation-of tube"'I98 as a result of the banking of the fuselage is not sumcient to completely offset' th'e'movementof the ball in tube I98 as a resultiof the banking of the fuselage. Consequentlyyball 202' will remain to the left of its heutrahposition with respect to wires 200, except for therfact that as the fuselage starts to bank touthe left, in accordance with good flying practicethe studentshould gradually return the stick to 'neutral and then apply a slight amount of rightstick'at the same time releasing the applied: left "rudder." Consequently, the final position-of-the apparatus is with the fuselage banked to the left, a slight amount of right stick being applied, with the rudder pedals centered. The ball 202 will be centered, and the trainer will be turning to theleft as a result of the conventional automatic turn with bank feature incorporated-intrainers of the type being considered. On the other hand, assuming that the student moves the control stick I00 to the right to place the. fuselage in asimulated right bank, the .link I46. moves to .the rear, rotating the arm I54 counterclockwise about the pivot I56 and rotating the 2 aIrm. I5.2 counterclockwise about the screw eye..26.0 .whichwill be held by the spring 266 and cable 24.4.. The bottom end of arm I52 moves ahead, as..does the bottom end of arm I60 which will" be moved about the screw eye 268 held by spring- 214 and cable 216, and the rear end of cablexI68 ''i released. The spring I pulling u'ponflthe' upper end of cable I68 results in a clockwise rotation of the arm I88 and inclincniete'r tube I98, as seen by the student, and the ball 202 moves to the right of the graduation upon the tube, thus indicating to the student that thetrainer is in a simulated slipping right bank; 'If'in order'to correct the improper bankingof the trainer, the student applies right rudder;""th'e link 238 moves to the rear releasing cable 244 and spring'266 will move the lower end"ofarm"l52 'to the rear, the arm pivoting about'the pin I50. The lower end of arm I60 alsowill'movetothe'rear, arm I60 pivoting about screw'eye 268 held by spring 214 and cable 216, resulting in a pulling upon the rear end of cable I68, and the-arm I88 and tube I98 will be rotated counterclockwise: as seen by the student in the trainer, thus returning the ball 202 toward its the instrument panel and tube I98 are tilted to the right, and the ball 202 moves to the right of its neutral position. By virtue of the fact that arm 290 remains vertical, and the distance from the lower end of arm. 290 to the stud 280 upon which pulley 218 is mounted decreases with a right bank, cable 216 is released resulting in a rearward movement of the upper end of arm I60, and in a pulling of cable I68, resulting in a counterclockwise rotation of tube I98. However, the counterclockwise rotation of tube I98 as a result of the banking to the right of the fuselage is not suflicient to completely offset the movement of the ball in tube I98 as a result of the banking of the fuselage. Consequently, ball 202 will remain to the right of its neutral position with respect to wires 200 except for the fact that as the fuselage starts to bank to the right, in accordance with good flying practice the student should gradually return the stick to neutral and then apply a slight amount of left stick, at the same time releasing the applied right rudder. Consequently, the final position of the apparatus is with the fuselage banked to the right, a slight amount of left stick being applied, with the rudder pedals centered, the ball 202 will be centered and the trainer will be turning to the right as a result of the conventional automatic turn with bank feature incorporated in trainer of the type being considered.

Assuming that the student in the trainer moves the left rudder pedal 222 ahead to turn the fuselage, but that the control stick I is retained in its neutral position, the link 238 moves ahead pulling cable 244 and resulting in a forward movement of the bottom of arms I52 and I60, arm I52 pivoting about pivot I50 and arm I60 pivoting about the screw eye 268 held by the spring 214 and cable 216. The forward movement of the lower end of arm I60 will release the cable I68 which will be pulled by the spring I95 resulting in a clockwise rotation of tube I98 and a movement of the ball 202 to the right of its neutral position, thus indicating to the student that the trainer is in a simulated left skidding turn. This situation may be corrected by a movement of the control stick I00 to the left which will move the link I46 ahead, and as previously explained cable I68 will be pulled so that the arm I88 and inclinometer tube I98 will be rotated counterclockwise back toward its neutral position, resulting in a returning of the ball 202 to its neutral position in tube I98. The application of the correct amount of left stick will result in a returning of the ball to its neutral position while an over-application of left stick will result in a movement of ball 202 beyond the neutral position, thus indicating to the student that the trainer is in a simulated slipping left turn and insuflicient application of left stick will not entirely eliminate the simulated skidding left turn.

The effect of banking of the fuselage upon the position of the ball 202 will be as previously explained, and the controls will be operated as previously set forth, to maintain the properly coordinated turn, once the same is established.

On the other hand, when the student in the trainer presses the right rudder pedal 224 ahead to produce a turning of the fuselage to the right, retaining the stick I00 in its neutral position, the link 238 moves to the rear releasing cable 244, and spring 266moves the lower end of the arm I52 to the rear, this arm pivoting about the pin I50, The movement to the rear of the lower end of arm I52 results in a similar movement of the lower end of arm I40, and cable I68 is pulled, resulting in a counterclockwise rotation of the inclinometer tube I98. The ball 202 moves to the left of its neutral position with respect to the inclinometer tube, thus indicating to the student that the trainer is in a simulated skidding right turn. Should the student then move the control stick I00 to the right to correct the faulty simulated turn, the link I46 moves to the rear, resulting in a clockwise rotation of the arm I88 and tube I98, resulting in a movement of ball 202 back toward its neutral position. The correct amount of applied left stick will center the ball 202 relative to tube I98; an over-application of right stick will move the ball 202 to the right past its neutral position in tube I98, thus indicating to the student that the trainer is in a simulated right slipping turn, and an insuificient application of right stick will not move ball 202 back to its neutral position, thus indicating a continuing right skidding turn.

The efl'ect of banking to the right of the fuselage upon the position of ball 202 will be as previously explained, and the controls should be properly operated, as hereinbefore set forth, to maintain the properly coordinated turn, once the same is established.

It will be appreciated that the indications given by the simulated inclinometer depend upon the banking position of the fuselage, and upon the position of cable I68, and that the position of cable I68 is responsive to the combined positions of the stick I00 and rudder pedals 222 and 224, as well as the banking position of the fuselage. Stick movement in one direction moves the cable I68 in one direction, while rudder movement in the same direction moves the cable I68 in the opposite direction, so that when the proper amount of stick and coordinated rudder are applied to commence the execution of a correctly coordinated left turn, the cable I68 is neutrally positioned and inclinometer tube I98 and ball 202 are centered to indicate a properly coordinated left turn. As the fuselage starts to bank, the ball would have a tendency to roll toward the direction of bank to indicate a slipping turn, but the application of a slight amount of opposite stick will recenter the ball, and this last motion may be coordinated with a neutralizing of the rudder pedals to keep the ball centered at all times.

Insofar as the reading of the simulated magnetic compass 2 I4 is concerned, any movement of the arm I88 from its neutral position as a result of the turning and banking of the fuselage will result in a rotation of the rotor 2I0 carrying the metallic elements 2 I6 to deflect the compass scale 2 I 4 to cause the compass indication to lead or lag the turning of the fuselage, thus simulating the northerly turning error to which real magnetic compasses in aircraft are subject.

It will be appreciated by those skilled in the art that many changes may be made of the disclosed embodiment of this invention Without departing from the substance thereof as covered by the following claims. All such changes are intended to be covered by the claims.

I claim:

1. In a grounded aviation trainer of the type having a fuselage mounted upon a universal joint for banking in simulation of the banking of a real plane in actual flight, and an instrument panel in said fuselage, the combination of an inclinometer tube and ball therein rotatably mounted near said panel, a differential device having an output member connected to said inclinometer tube for rotatably positioning the same, a first manual control in said trainer simulating the banking control of a real plane, a left and a right rudder pedal in said fuselage simulating the rudder pedals of a real plane, a connection between said first manual control and said differential device and a connection between said rudder pedals and said differential device for operating said output member to position said inclinometer tube in accordance with the combined positions of said first manual control and said rudder pedals, and means responsive to the banking of said fuselage connected to said differential device for rotating said tube clockwise in response to a banking to the left of said fuselage and counterclockwise in response to a banking to the right of said fuselage.

2. The structure set forth in claim 1 in which the connections and differential device are arranged so that a movement of the first manual control to the left rotates the inclinometer tube counterclockwise and a movement to the right rotates the inclinometer tube clockwise, while a forward movement of the left rudder pedal ro- REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,099,857 Link Nov. 23, 1937 2,243,973 Mills 1 June 3, 1941 2,336,711 Barber Dec. 14, 1943 2,366,603 Dehmel M Jan. 2, 1945 2,409,238 Barber Oct. 15, 1946 FOREIGN PATENTS Number Country Date 396.540 Great Britain Aug. 10. 1933 

